e8467cd31c
Instead of checking the loopback ioctls, let's check sysfs, so that we catch all kinds of block devices, not just loopback block devices.
254 lines
7.4 KiB
C
254 lines
7.4 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <sys/file.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "blockdev-util.h"
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#include "btrfs-util.h"
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "missing_magic.h"
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#include "parse-util.h"
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#include "stat-util.h"
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int block_get_whole_disk(dev_t d, dev_t *ret) {
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char p[SYS_BLOCK_PATH_MAX("/partition")];
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_cleanup_free_ char *s = NULL;
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dev_t devt;
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int r;
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assert(ret);
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if (major(d) == 0)
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return -ENODEV;
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/* If it has a queue this is good enough for us */
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xsprintf_sys_block_path(p, "/queue", d);
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if (access(p, F_OK) >= 0) {
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*ret = d;
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return 0;
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}
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if (errno != ENOENT)
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return -errno;
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/* If it is a partition find the originating device */
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xsprintf_sys_block_path(p, "/partition", d);
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if (access(p, F_OK) < 0)
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return -errno;
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/* Get parent dev_t */
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xsprintf_sys_block_path(p, "/../dev", d);
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r = read_one_line_file(p, &s);
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if (r < 0)
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return r;
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r = parse_dev(s, &devt);
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if (r < 0)
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return r;
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/* Only return this if it is really good enough for us. */
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xsprintf_sys_block_path(p, "/queue", devt);
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if (access(p, F_OK) < 0)
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return -errno;
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*ret = devt;
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return 1;
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}
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int get_block_device(const char *path, dev_t *ret) {
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_cleanup_close_ int fd = -1;
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struct stat st;
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int r;
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assert(path);
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assert(ret);
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/* Gets the block device directly backing a file system. If the block device is encrypted, returns
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* the device mapper block device. */
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fd = open(path, O_NOFOLLOW|O_CLOEXEC);
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if (fd < 0)
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return -errno;
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if (fstat(fd, &st))
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return -errno;
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if (major(st.st_dev) != 0) {
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*ret = st.st_dev;
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return 1;
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}
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r = btrfs_get_block_device_fd(fd, ret);
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if (r > 0)
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return 1;
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if (r != -ENOTTY) /* not btrfs */
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return r;
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*ret = 0;
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return 0;
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}
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int block_get_originating(dev_t dt, dev_t *ret) {
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_cleanup_closedir_ DIR *d = NULL;
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_cleanup_free_ char *t = NULL;
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char p[SYS_BLOCK_PATH_MAX("/slaves")];
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struct dirent *de, *found = NULL;
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const char *q;
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dev_t devt;
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int r;
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/* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
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* trying to find the next underlying layer. */
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xsprintf_sys_block_path(p, "/slaves", dt);
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d = opendir(p);
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if (!d)
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return -errno;
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FOREACH_DIRENT_ALL(de, d, return -errno) {
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if (dot_or_dot_dot(de->d_name))
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continue;
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if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
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continue;
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if (found) {
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_cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
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/* We found a device backed by multiple other devices. We don't really support automatic
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* discovery on such setups, with the exception of dm-verity partitions. In this case there are
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* two backing devices: the data partition and the hash partition. We are fine with such
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* setups, however, only if both partitions are on the same physical device. Hence, let's
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* verify this. */
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u = path_join(p, de->d_name, "../dev");
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if (!u)
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return -ENOMEM;
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v = path_join(p, found->d_name, "../dev");
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if (!v)
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return -ENOMEM;
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r = read_one_line_file(u, &a);
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if (r < 0)
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return log_debug_errno(r, "Failed to read %s: %m", u);
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r = read_one_line_file(v, &b);
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if (r < 0)
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return log_debug_errno(r, "Failed to read %s: %m", v);
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/* Check if the parent device is the same. If not, then the two backing devices are on
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* different physical devices, and we don't support that. */
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if (!streq(a, b))
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return -ENOTUNIQ;
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}
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found = de;
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}
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if (!found)
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return -ENOENT;
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q = strjoina(p, "/", found->d_name, "/dev");
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r = read_one_line_file(q, &t);
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if (r < 0)
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return r;
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r = parse_dev(t, &devt);
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if (r < 0)
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return -EINVAL;
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if (major(devt) == 0)
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return -ENOENT;
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*ret = devt;
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return 1;
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}
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int get_block_device_harder(const char *path, dev_t *ret) {
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int r;
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assert(path);
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assert(ret);
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/* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
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* immediate parent, if there is one. */
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r = get_block_device(path, ret);
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if (r <= 0)
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return r;
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r = block_get_originating(*ret, ret);
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if (r < 0)
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log_debug_errno(r, "Failed to chase block device '%s', ignoring: %m", path);
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return 1;
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}
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int lock_whole_block_device(dev_t devt, int operation) {
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_cleanup_free_ char *whole_node = NULL;
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_cleanup_close_ int lock_fd = -1;
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dev_t whole_devt;
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int r;
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/* Let's get a BSD file lock on the whole block device, as per: https://systemd.io/BLOCK_DEVICE_LOCKING */
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r = block_get_whole_disk(devt, &whole_devt);
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if (r < 0)
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return r;
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r = device_path_make_major_minor(S_IFBLK, whole_devt, &whole_node);
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if (r < 0)
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return r;
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lock_fd = open(whole_node, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
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if (lock_fd < 0)
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return -errno;
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if (flock(lock_fd, operation) < 0)
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return -errno;
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return TAKE_FD(lock_fd);
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}
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int blockdev_partscan_enabled(int fd) {
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_cleanup_free_ char *p = NULL, *buf = NULL;
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unsigned long long ull;
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struct stat st;
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int r;
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/* Checks if partition scanning is correctly enabled on the block device */
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if (fstat(fd, &st) < 0)
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return -errno;
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if (!S_ISBLK(st.st_mode))
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return -ENOTBLK;
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if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
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return -ENOMEM;
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r = read_one_line_file(p, &buf);
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if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
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* partition block device, not the whole block device. And that means we have no
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* partition scanning on for it (we do for its parent, but not for the partition
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* itself). */
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return false;
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if (r < 0)
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return r;
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r = safe_atollu_full(buf, 16, &ull);
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if (r < 0)
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return r;
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#ifndef GENHD_FL_NO_PART_SCAN
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#define GENHD_FL_NO_PART_SCAN (0x0200)
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#endif
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return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
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}
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